Expression of CD80 and CD86 by spleen B cells in response to MADB106 tumor. Total spleen cells were incubated in the presence of MADB106 tumor cells. The expression of CD80 and CD86 on B cells (gated on CD45RA+ cells) was determined using flow cytometry. Vertical bars and error bars represent the mean ± SE (n = 6). Asterisks indicate statistical difference (P less than or equal to 0.05) in CD80 and CD86 molecule expression by spleen B cells in the presence or absence of MADB106 tumor.